Bone is a living tissue and plays a structural role in the body. A bone fracture is a medical condition in which a bone has cracked or broken. While many fractures are the result of high force impact or stress, bone fracture can also occur as a result of certain medical conditions that weaken the bones, such as osteoporosis, certain types of cancer or osteogenesis imperfecta. The average person sustains two to three fractured bones during the course of a lifetime. Fracture repair is the process of rejoining and realigning the ends of broken bones. Currently there are several internal approaches to repair, strengthen and support a fractured bone.
Conventional internal fixation devices include wires, plates, rods, pins, nails, and screws to support the fractured bone directly, as well as the addition of bone cement mixtures, or bone void fillers to the fractured bone. For example, one common device includes a thick rod, or a plurality of thinner rods, which are implanted into the medullary cavity of the broken bone to stabilize the placement of the bone fragments once they are set in place. In order for these rods to function properly upon implantation, however, they must fit tightly within the medullary cavity. This fit is usually achieved by boring or reaming the cavity to obtain a constant diameter, widened cavity in which the rod is inserted.
Newer internal fixation devices include expandable members in which an outer surface of the device contacts the interior surface of the medullary cavity which leads to greater support and strength to the healing bone. Drawbacks to the present techniques for using these expandable members include the guess work involved in fitting the expandable member within the medullary cavity available. For example, since a medical professional cannot see into the cavity space, there is a lack of knowledge as to the size of the available space in the cavity and the exact pressure needed to expand the member. If too much pressure is exerted on the expandable member, necrosis of bone along the entire length of the fractured bone is possible. Also, since most of the expandable members presently available are pre-sized, an expandable member that does not conform to the cavity space available may be used, resulting in an improper fixation of the fractured bone and poor healing.
Therefore, there is a need in the art for a device that can be used prior to inserting an expandable member within the medullary cavity space that can predict the size of the cavity. This pre-procedure sizing will enable custom fit bone fixation pins and lead to advantageous healing conditions.